#include"Delay.h"
#include <REGX52.H>

unsigned char key()
{
  unsigned char keynum=0;
	if(P3_1==0)
	{
		Delay(20);
		while(P3_1==0);
		Delay(20);
		keynum=1;
	}
	if(P3_0==0)
	{
		Delay(20);
		while(P3_0==0);
		Delay(20);
		keynum=2;
	}
	if(P3_2==0)
	{
		Delay(20);
		while(P3_2==0);
		Delay(20);
		keynum=3;
	}
	if(P3_3==0)
	{
		Delay(20);
		while(P3_3==0);
		Delay(20);
		keynum=4;
	}
	return keynum;
}